Anatomical organization of the Brain. Support is requested for continuing investigation of the comparative neuroanatomy of vertebrate brains. During the forthcoming grant period outlined, studies will concentrate on three major subjects: a) Organization of the Optic Tectum: afferent/efferent connections and histochemistry; b) Descending connections of the Basal Ganglia with particular emphasis upon neuropeptides in the nucleus Spiriformis Lateralis (SpL) and its projection upon the optic tectum; and c) Sensory and motor representation of individual visceral organs in the vagus (nucleus solitarius and visceral motor nuclear) complex: connections and histochemistry. Methods include Horseradish Peroxidase (HRP) for anterograde and retrograde studies, tittriated amino acids for antrograde transport Autoradiography (ARG), Immunohistochemistry (IHC) of peptides and Electron Microscopy (EM).